Biology Qbank 10 Question 11

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uvwaves21
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Joined: Fri Feb 09, 2018 5:23 pm

Biology Qbank 10 Question 11

Post by uvwaves21 » Tue Mar 27, 2018 2:31 pm

The restriction point, or the point at which a cell is committed to undergoing mitosis, is located in which stage of interphase?

A. G0
B. S
C. G1
D. G2

The explanation states: C is correct. The restriction point is a point in G1 of the cell cycle, and after it is passed the cell is committed to division.

I thought it is not committed until it passes G2? If the damage at that checkpoint is irreparable prior to mitosis at G2, the cell may undergo apoptosis or programmed cell death? How is the correct answer G1?
NS_Tutor_Andrew
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Re: Biology Qbank 10 Question 11

Post by NS_Tutor_Andrew » Wed Mar 28, 2018 11:15 am

Hi uvwaves21,

To the best of my knowledge, sources are quite consistent about referring to the G1 checkpoint as the restriction point and the point where the cell is committed to division. In addition to Wikipedia, it appears in more authoritative sources, such as this review published in Cell Cycle and this more recent review. So how does G2 fit in? Basically, the G1 checkpoint means that the cell is committing to division, but it's not necessarily committing to doing it successfully. The G2 checkpoint has to do with whether the cell succeeds -- but if it fails, it can't just go back to G0. This may be somewhat dark humor, in which case please forgive me, but the analogy comes to mind that the G1 checkpoint is like clicking "submit" on med school applications, and G2 is like the admissions process itself.

Hope this helps, and please do let me know if there are any sources that point in a different direction!
Andrew D.
Content Manager, Next Step Test Prep.
uvwaves21
Posts: 11
Joined: Fri Feb 09, 2018 5:23 pm

Re: Biology Qbank 10 Question 11

Post by uvwaves21 » Sat Mar 31, 2018 7:04 pm

Thank you, Andrew! I understand it much better now, especially with the analogy.
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